1. Field of the Invention
The present invention generally relates to agricultural irrigation. More specifically, embodiments of the present invention pertain to methods and apparatuses for indicating when irrigation water has flowed to a certain position.
2. Background and Description of Related Art
Flood irrigation of fields, and particularly fields of agricultural produce arranged in rows, typically is accomplished by a plurality of ditches or trenches. In some applications, such as in grape vineyards, narrow trenches extend alongside, and parallel with, one or both sides of a row of plants. In some other applications, such as in almond orchards, a ditch may comprise the entire area between adjacent rows of plants. Other examples of fields where trenches or ditches are used include, without limitation, fields where corn, cotton, melons, tomatoes and other plants are grown. Flood irrigation is also used in open fields such as those used for growing grain or alfalfa. These fields are ordinarily divided by small berms that run the length of the field. These berms form areas known commonly referred to as a “check”. These “checks” may be sixty feet (60′) wide, or wider in some cases, and may be as long as one quarter (¼) mile.
In some situations, a water inlet valve may be provided on at least one end of a ditch, trench or check. In other situations, an irrigation ditch or canal may be adjacent to the field, and siphon pipes are used to draw water out of the irrigation canal and into the trenches, ditches or checks of the field. In some situations, the ditch or trench may have a “U” shaped path such that it wraps around the end of the row opposite to the water inlet location.
When it is desired to irrigate a field, an irrigator can open a water inlet valve, or initiate a siphon using tubes, thereby discharging water into one end of the ditch, trench or check. Water in the ditch, trench or check advances through gravitational forces. Once the water reaches the end of the ditch, trench or check, if it has not been shut off, it may wrap around the row (for wrap-around designs), overflows onto the adjacent land, or result in ponding.
Rows of agricultural plants can span a significant length, perhaps 500 meters. Thus it is to be appreciated that, depending on the width of the trench or check, and the volumetric flow rate of the water inlet, it may take a significant amount of time for the irrigation water to completely fill the trench or check by traversing from one end to the other. Moreover, it is to be appreciated that because the water flows from one end of the trench of check to the other by gravity (i.e., the water will continue to flow until it has equalized in the trench or check), the flow of water may not instantaneously stop. This flow is sometimes referred to as a “head.” For these reasons, it is necessary for an irrigator to close the water inlet valve before the water reaches the end of the trench or check.
After the valve is closed, water will continue to flow through the trench, ditch or check until equalized. It is preferable that this flow stop at the end without overflow. Conventionally, to prevent overflow (and thus prevent waste) of the irrigation water, the irrigator has another person stand a distance down the row and monitor the flow of water. When the flow of water reaches a determined point, the monitor can signal to the irrigator (for example, by a visual signal such as raising their hand or by an audio signal such as shouting) to shut off the water. For example, the pre-determined position may be about ¾ of the way down the row of a trench. The signaling person watches that position, and indicates when the flow of water in the trench has reached that position. In response to the signal, the irrigator shuts off the flow of water which then equalizes, with the head flowing to the end of the trench.
In many areas where water resources are scarce, overflow of water has caused flood irrigation to come under increased scrutiny. Pumping unnecessary water is expensive and wasteful. In addition, the labor cost of having a worker monitor the flow of water can be cost prohibitive.
It is therefore desirable to conserve water by providing apparatuses and methods for indicating when water flow in an irrigation check, trench or ditch has reached a predetermined position without the need for additional monitoring personnel.